Thermodynamically-controlled pendent switch for electric circuits



MALCOLM H. BAKER, DECD.

MARIE HfB/LKER, ADMINISTRATRIX. THERMODYNAMICALLY CONTROLLED PENDEN? SWITCH FOR ELECTRIC CIRCUITS.

APPLICATION FILED OCT. 21, 1915. RENEWED APR. 14.1919. 7

1 28,480, Patented J an. 20, 1920.

MALCOLM H. BAKER, BRAINTREE, MA

TBATBIX OF SAID MALCOLM H. BAKER,

SSACHUSETTS; MARIE H. BAKER, ADMINIS- DECEASED, ASSIGNOR TO KENNETH W.

CROSBY, TRUSTEE, 013 BOSTON, MASSACHUSETTS.

THEBMODYNAMICALLY-CONTROLLED PENDEN T SWITCH FOR ELECTRIC CIRCUITS.

Specification of Letters Patent.

Patented J an. 20, 1920.

Application filed October 21, 1915, Serial No. 57,104. Renewed April 14, 1919. Serial No. 290,085.

To all whom it may concern:

Be it known that I, MALCOLM H. BAKER, a citizen of the United States, and a resident of Braintree, in the county of Norfolk and Commonwealth of Massachusetts, have invented certain new and useful Improvements in Thermodynamically- Controlled Pendent Switches for Electric Circuits, of which the following'is a specification.

My invention relates to switches for electric circuits, and particularly to such switches when of the pendent type, adapted to be controlled by push button mechanism.

The object of my invention is to provide a endent switch to control electric lights or other apparatus of the usual pendent form, and controlled by the usual push buttons to open and close the circuit,but which is further ada tedto retain the circuit closed a brief an predetermined time after the button adapted to open the circuit has been actuated.

In other applications filed by me I have illustrated and broadly claimed such type of time retarded switch control as broadly applicable to various Well known types of switches for electric circuits; and specifically as a plicable to snap switches, socket switches, ife switches, and various other forms. e

I have illustrated a preferred form of my invention in the accompanying drawings, in which: Figure 1 is a plan View of my im proved pendent switch taken in section on the horizontal plane A-A in Fig. 2; Fig. 2 is a vertical section taken through the switch on the plane BB in Fig. 1; Fig. 3 is an elevation looking at the right of Fig. 2, with the casing partially broken away and showing certain switch parts in section on the vertlcal plane 0-0 in" Fig. 2; and Fig. 4 is a diagram of electrical connections.

Throughout the drawings the same part when appearing in different views is designated by the same reference numeral and so referred to in the following description.

In'the drawings the push button adapted to close the switch appears at 2 and the opening button at 1, said buttons being mounted on opposite ends of the sliding shaft 3 which is guided in bracket 4 mounted upon top piece 5 which is preferably of porcelain. This shaft 3 carries, fixed to it, a metal piece 10 and a similarly shaped piece 11 composed of insulating material, these pieces being adapted to engage with spring clips 12, 13 as a detent, so as to snap into and out of such engagement as the control buttons 1, 2, are respectively pushed. The members 12,13, are mounted upon a base piece 6, preferably of porcelain. A thermostat, of the usual bi-metallic construction, appears at 16, with a resistance winding 17, suitably insulated therefrom, and is mounted upon a bracket 15 attached to the base 6 and top 5. This bracket also carries a spring member 14 attached to a main contact 22 adapted normally to separate from a second main contact 18 attached to the bracket 7 on the pieces 5-, 6. An extension 21 is attached to the shaft 3 and reaches down into engagement with the member 22 to push the same into contact with the member 18, said contact being maintained by the pressure of the clips 12, 13, on the piece 10.

A casing 8, 9, incloses the switch, and the line wires are attached to binding posts 19, 20, in the usual manner.

Operation of the switch is as follows: When the button 2 is pushed to close the switch the metal piece 10 is pressed against the members 12, 13, and slips between them with a marked snap, while at the same time the extension 21 pushes the member 22" against the member 18 to close these contacts. The resistance 17 is shunted by the engagement of the member 10' with clips 12, 13, so that said resistance is practically dead, and the switch operates in the usual manner.

While the member 22 is being pushed into engagement with the member '18 its end passes past the end of the thermostat 16, the said thermostat giving, or sprin ing, slightly to permit such passage and to t ereafter return to a position in the line of movement of member 22.

It will be noted that no load is placed upon the thermostat during normal operation of the switch since the member 22 is maintained clear of the end of the said thermostat during such operation.

To open the switch, the button 1 is pushed which moves the piece 10, with a snap, out of engagement with the clips 12, 13, and pushes the companion piece 11 into such enby a resistance winding wound thereon, it

clips 12, 13, is now opened,-that is, the shunt circuit around the winding 17 is opened,-'whereby said winding is placed solely in series with the switch controlled circuit. The thermostat is now heated, and bends to release the member 22 to open the circuit, the said member having moved into engagement with the said thermostat on the withdrawal of the extension 21. By these means the circuit is opened with a quick break movement as desired.

It is evidentthat the time interval between the push on the button 1 and the opening of the circuit is attained by the time needed to heat to operation the thermostat 16, and that this interval may be readily varied by varying the winding 17, or the construction of the thermostat, or the degree of engagement thereof with the member 22.

While I have illustrated the thermostat as being of bi-metallic form and energized is evident' that any suitable form of thermo dynamic device might be employed, and that the heating element might comprise a resistance of some other type.

Without therefore, limiting myself to the precise embodiment of my invention herein illustrated, what I claim is,-

1. In an electric switch, the combination with main. circuit controlling contacts adapted normally to open, and thermostatic control means arranged to be electro-thermally operated for governing the opening of-said contacts, of a manually operable control rod arranged for longitudinal, reciprocative movement between switch closing and switch opening positions thereof, mechanism arranged to be operated by said rod for closing said contacts, detent means arran ed yieldingly to hold said rod in the sai two positions thereof, and a circuit controlling device connected electrically to govern said means and positioned to be operated by said rod;whereby in the switch closing position of said rod, said means are deenergized and thereby positioned to prevent opening of said contacts when said rod is moved to its said switch-opening position, and whereby movement of said rod to its said latter position energizes said means for permitting the opening of said contacts after a predetermined time.

2. In an electric switch, the combination with main circuit controlling contacts adapted normally to open, and thermostatic control means arranged to be electro-thermally operated for governing the opening of said contacts, of a manually operable control rod arranged for longitudinal, reciprocative movement between switch closing and switch -opening positions thereof, mechanism arranged to be operated by said rod for closing said contacts, and an auxiliary circuit controlling device connected electrically to govern said thermostatic control means and mechanically formed to co-act' said rod, said means are denergized and thereby positioned to prevent opening of said contacts when said rod is moved to its said switch-opening position, and whereby movement of said rod to its said latter position energizes said means to permit the opening of said contacts after a predetermined time.

3. In an electric switch, the combination with main circuit controlling contacts adapted normally to open, and thermostatic control means arranged to be electro-thermally operated by an auxiliary circuit for governing the opening of said contacts, of a manually operable control rod arranged for longitudinal, reciprocative movement between switch-closing and switch-opening positions thereof, a member depending from said rod and arranged by movement therewith to close said contacts by engagement with one thereof when said rod is moved to its switchclosing position, detent means arranged yieldingly to hold said rod in the said two. positions thereof, and a circuit controlling devlce connected electrically to govern sai means and positioned to be operated by said rod ;whereby in the switch-closing position of said rod, said means are deenergized and thereby positioned to prevent opening of said contacts when said rod is moved to its said switch-opening position, and whereby such movement of said rod energizes said means for permitting the opening of said contacts after a predetermined time.

4. A thermostatically controlled circuit switch, embodying in combination with a contact member, and a resiliently mounted coiiperative second contact member; manual controlling means for said'switch comprising a push rod mounted for longitudinal, reciprocative movement between circuit-closing and circuit-opening positions thereof and arranged to push the-said second member into contact with the said first member to close the circuit, a thermostatically controlled detent positioned when said push rod occupies its said circuit-closing position to lie in the path of movement of said second contact member and thereby adapted to hold said second member in contact with said first member when said rod is moved out of said circuit-closing position thereof, a detent arranged to hold said rod in a yielding manner at each extreme of its movement, and an electric heater for the thermostat, said heater being provided with circuit connections arranged to be operatively controlled by said push rod ;-whereby movement of the latter to its said circuit-opening p'ositionenergizes the thermostat for causing delayed opening of the circuit.

5. A thermostatically controlled circuit switch, embodying in combination with a contact member, and a resiliently mounted, cooperative contact member; manual controlling means for said switch comprising a push rod mounted for longitudinal, reciprocative movement between circuit-closing and circuit-opening positions thereof and arranged to move, and automatically to hold, the said second member in contact with the said first member to close the circuit, a thermostatically controlled detent positioned when said push rod occupies its said circuitclosing Position to lie in the path of movement 0 said second contact member and thereby adapted to hold said second member in contact with said first member when said rod is moved. out of said circuit-closing position thereof, a detent to hold said rod in a yielding manner at each extreme of its movement, and an electric heater for the thermostat, said heater being provided with circuit connections arranged to be operatively controlled by said push rod ;whereby movement of the latter to its said circuitopening position energizes the thermostat for causing delayed opening of the circuit.

6. In an electric circuit switch, in combination with automatic switch opening mechanism embodying contact members with resilient connection to tension same for relative separation thereof, a thermostat arranged when thermally denergized to prevent separation of said members and further adapted (upon energization thereof) to permit said separation, a heater for the thermostat adapted to be electrically energized, manually operable switch-controlling means comprising a push rod mounted for longitudinal, reciprocative movement, with mechanism controlled thereby to close the switch, and an auxiliary circuit-controlling device operative upon reverse movement of said rod to energize said heater, thereby to permit delayed automatic opening of the switch.

Signed at Boston, in the county of Suffolk and Commonwealth of Massachusetts, this 19th day of October, 1915.

MALCOLM H. BAKER. Witnesses:

R. D. SMITH, Smvro AMOROSO. 

